Work is being carried out in the following areas: 1. Neuroectodermal etiology of gastrointestinal related endocrinopathies - tissue tagging technique in mice. 2. Calcium ion regulation of secretory activity of G.I. - endocrine cells - in-vitro frog gastric membrane preparation with radioisotopic tagging and stimulation with calcium ion and pentagastrin. 3. Regulation of gastrin release from antrum - animal and human study measuring gastrin release with pH changes in intraluminal antral area. 4. Humoral similarities of endocrine tumor elaborations - clinical study 5. Effect of vasoactive and humoral substances on oxyhemoglobin dynamics.